1. Field of the Invention
One of the long standing problems associated with display of information received from a scene is that the imagery presented by the cathode ray tube does not have a sufficiently high contrast. Imagery with a high contrast is especially necessary for detection and recognition of ground targets such as when an operator in an aircraft or helicopter slews his line of sight during a ground search. If the video which may be from an infrared detector system is not optimal, during an entire ground search, many potential targets are not detected or recognized by processing elements or by an operator. A display system, for example, characteristically has a much smaller dynamic range than the sensor and therefore superfluous sensor data should not be presented for display. If the output from the sensor were applied to the display so as to occupy the entire dynamic range of the display (black to white) a high contrast and easily readable picture would be provided.
2. Description of the Prior Art
The function of controlling the level and gain of the display which is performed automatically by the system of the invention was previously done manually by the operator controlling two potentiometers. Manual control to optimize the video is usually updated only when the signal is substantially degraded, especially when the operator is engaged in slewing the line of sight and searching for targets. Thus the prior art systems did not continuously provide a desirable high contrast video.